Author 




Title 



Class 



Book 



.Caff 



Imprint 



v 



♦ 






REPORT 



6 



■ 



Imtrd of yate jjjarkr ■ ^mntission^s 



OX THE 



PRESERVATION OF TIMBER. 



By T . J, ARNOLD 

ENGINEER OF THE SEA WAIX. 



SAN FRANCISCO, CAL. 
V- JOS. WINTEEBUEN & CO., PEINTEES AND ELECTS OTYPEES. <^> 









No. 417 Clay Street, between Sansorne and Battery. 
I§73- 






fc*^*?^ 



^uT 






*oatd of jf/#/£ $§arbor ^ott[minniot\tr$, 



LEWIS CUNNINGHAM, 
SAMUEL SOULE, 
JOHN ROSBNFELD. 



j. a. McClelland, 

Secretary. 
\ 



*>& 






REPORT. 



Engineer's Office, ) 

San Francisco, February 3rd, 1873. j 

To the Honorable, the Board of State Harbor Commissioners — 

Gentlemen: In compliance with your instructions, I have 
examined the subject matter of the communication from I. C* 
Woods, Esq., manager of the wood preserving works located in 
this city, and also that of Thos. C. Wallace and Co. and respect- 
fully submit the following report: 

The preservation of woods by means of chemical preparations, 
has been the subject of many interesting experiments both in the 
United States and in Europe. From the nature of the investiga- 
tions, the value of the several processes which have been suggested, 
can only be ascertained by actual trial after such tests as time 
alone can furnish. No experiments that I have made myself can 
therefore, be of any material interest, and in the discussion of the 
question I am driven to the necessity of referring you almost en- 
tirely to what has been done by others. As the subject is one of 
great importance in its bearing upon projected improvements on 
our water front, I trust I may be pardoned for treating it some- 
what at length. 

The destruction of our wharves arises from two causes : 
First — The marine worms which feed upon the piles, and 
Second — The rapid decay of the Oregon fir timber composing 
the superstructure. 

The marine worms which destroy our piles are of two kinds, 
namely, the Teredo Navalis and the Limnoria Terebrans. 

The operations of the Teredo have been pretty thoroughly ob- 
served by scientific men, but the habits of the worm itself have 
not been so well studied. So far as I know, the germ of the 
Teredo, seems to exist in all sea water above a certain temperature, 
but its presence there cannot be detected, even under the magni- 
fying power of the most powerful microscope. It needs for its 
development, a habitation of wood from which the bark has been 
removed. A series of interesting experiments were made at the 
Norfolk Navy Yard, prior to 1861, by Calvin Brown, Esq., now 
Government Civil Engineer at Mare Island. In the course of these 
experiments, he found that the young Teredo, had entered a piece 
of wood one-eighth of an inch in thickness, which had only been 
submerged eight days. The outer surface of the wood under the 



microscope showed no signs of perforation by the worm but a thin 
shaving planed off, exposed their holes, though not visible with- 
out the glass. Deeper excavation, brought to light the worm 
itself, which was then so small as to be nearly invisible to the naked 
eye It appeared to be a small white bulb, but under the glass 
it showed the perfect Teredo. This germ would grow at Norfolk 
from six to twelve inches in length and three-eighths of an inch 
in diameter during one summer. 

The Teredo has neither legs, fins nor other apparent means of 
locomotion. Its head, which is in two parts, is of the ordinary 
sea shell substance and fills one end of the cavity it inhabits. 
The wood is bored by the head, its two parts working on a hinge, 
into fine dust, which passes through the gelatinous body of the 
worm, perhaps furnishing it food. This gelatinous body entirely 
fills the cavity made and inhabited by the worm. The body term- 
inates in a flattened tail protected by a thin shell covering. At 
its junction with the body the tail can be opened into two equal 
parts, indicating one straight intestine from the head to and 
through the tail. The Teredo can at will project this tail through 
the hole by which it entered the wood, and this is its means of 
communication with the sea water. Without sea water, if allowed 
to remain in the wood, the worm dies in from 24 to 48 hours; re- 
moved from the wood it dies almost instantly and its body shrivels 
to a mere thread. 

The Teredo is said by naturalists to be oviparous, and that its 
young, immediately after birth, attach themselves to the first 
attainable wood, and begin to bore it. Whether they impreg- 
nate the waters of the harbor by being brought into it in worm- 
eaten wood, or whether after leaving the mother they remain in 
an imperfect condition in the water for an indefinite period until 
they drift against a piece of wood floating or fixed; or whether 
the young teredo forms a living colony in the honey-combed 
piles, are among the habits of this destructive pest, which are 
yet to be investigated. 

In our Eastern harbors they are said to disappear during the 
Winter months, or at least to cease their ravages, and then to 
re-appear or recommence their operations with the opening of 
Summer. In this harbor they never cease their operations so far 
as we have been able to observe their habits. 

The Teredo enters the piles across the grain of the wood, 
between the top of the mud and ordinary low water mark, 
and after entering, it bores with the grain upward, as far as high 
water mark, and downward to the line of the mud; but never 
below the line of the mud and never out again into the water. 

The Teredo, as I have before mentioned, never eats the bark 
of the wood, and only enters the piles after the bark has been 
removed. 



The Limnoria Terebrans has only recently made its appearance 
in our waters. It comes originally from the tropics and is brought 
here no doubt by vessels whose planking has been eaten by it. 
This worm cuts the piles entirely across the grain, eating from 
the outside, and making great cavities in the wood. They seem 
to prefer being left exposed a portion of the time by the receding 
tide. It eats the wood just below ordinary high water mark. 

This worm was first noticed in England in 1808, by the late 
Robert Stevenson, and was named and described by Dr. Leach in 
1811. The following is the description of the Limnoria as found 
in English waters : 

" Gregarious and abundant; attacks by preference the pine 
family; does not attack floating wood; is from i to ^ of an inch 
long, rounded at each end, with parallel sides; has fourteen seg- 
ments, the last two being the largest; the seven next to the head 
each bear a pair of strong mandibles which are the boring organs. 
General color olive grey; can swim as well as creep; when touched 
rolls itself into a ball like the common sow bug which it much 
resembles." 

This description answers precisely to the newly discovered 
worm which has so recently made its appearance in the waters of 
this harbor. Piles are eaten by them completely through, so 
that one piece will remain attached to the cap of the wharf while 
the other is found projecting from the mud. The operations of 
this worm may be seen at North Point and Greenwich Docks. 

THE DECAY OF OREGON FIR TIMBER IN SAN FRANCISCO. 

The best authorities agree as to the winter months, when the 
sap is down, being the time for cutting timber in order to secure 
the best quality of material which the tree is capable of produc- 
ing. They also agree as to the necessity of thoroughly seasoning 
this same wood before using it. Our wharf material here is often 
growing in the forests bordering Puget Sound ninety days before 
it is framed into the wharf. In an exhaustive report made by 
Chas. R. Story, Chairman of Special Committee, addressed to the 
Board of Supervisors of this city, July 30th, 1870, upon the sub- 
ject of street pavements, he uses the following language in 
reference to timber on this coast: 

" The time of year within which trees are felled has very great 
influence on the durability of the wood. To secure the best 
qualities of the wood the tree should be felled when the sap is 
down, that is, in the winter months. It is this fact which makes 
the winter months the season for logging. In the East the snow 
forms the bed for hauling the logs, and the swollen rivers in the 
spring carry the logs to market. In this country we have neither 
winter nor snow, and but few rivers used for rafting; hence on 
the Pacific Coast, the timber trees are cut at all seasons of the 
year, and beyond doubt a portion of the bad reputation attaching 



to some species of wood is owing to this cause. Nearly all the 
wood brought to this market comes by vessel, green, and of 
course steamed in the hold, hence may be injuriously affected 
by this confinement. We can never bring logging to the system 
of winter cutting practiced in the East, and this is an additional 
reason why, in San Francisco, we must resort to some wood pre- 
serving process to protect us against decaying wood." 

In our own experience, on works under the control of the 
Harbor Commissioners, we have found that piles are attacked by 
the teredo, as soon as the bark falls off, which is in about two years 
after they are driven; that fender piles are so weakened by these 
attacks, that in four years they will not sustain any considerable 
lateral pressure; that standard piles, having to sustain a vertical 
pressure will last from seven to eight years, but at some risk 
after the sixth year, and that Oregon timber, when exposed to 
moisture, begins to decay in from five to eight years. 

Having glanced at the causes of the rapid destruction of our 
wharves, I will now consider what may be done to preserve them 
from decay and the ravages of the marine worm. 

Upwards of fifty patents have been taken out for the preserva- 
tion of timber by chemical preparations, the mode of application 
generally being, to force the solutions into the pores of the wood 
by pressure in close vessels. The best known, and perhaps most 
valuable compounds employed, are Chloride of Mercury, Sulphate 
of Copper, Chloride of Zinc, Sulphate of Iron, Carbonate of 
Soda, and Creosote or Pitch Oil. While some of the metallic 
salts have be,en found to prevent dry rot, none of them appear to 
protect submerged timbers from the attacks of the marine worms. 
Prof. Wood, of the Michigan University, in a recent treatise on 
the preservation of timber, says: "It was naturally supposed 
that poisoning the timber would poison or drive away the teredo, 
but Ryan's and all other processes employing solutions of the 
salts of metals of alkaline earths, signally failed. The constant 
motion of sea water soon dilutes and washes away the small 
quantity of soluble poison with which the wood has been injected. 
If any albuminate of a metalic base still remains in the wood, the 
poisonous properties of the injection have been destroyed by the 
combination. Moreover, the lower vertibrates are unaffected by 
poisons which kill the mammals. Indeed it is now known that 
certain of the lower forms of animal life, live and even fatten on 
such deadly agents as arsenic/' 

A paper read at a meeting of the Philosophical Society, of 
Glasgow, by Mr. P. M. Moir, and published in 1869, contains a 
concise statement of the conclusions arrived at relative to the 
value of the various European patents for preserving wood from 
the attacks of the marine worm, and is, in a measure, a sum- 
mary of the opinions of nearly all recent writers on the subject, 
He says: 



' ' Kyanizing or injecting corrosive sublimate into timber is 
very expensive, if properly done, and besides this, there is the 
fact that it is practically useless, inasmuch as it has been found 
that Kyanized piles after three years of immersion in the sea, did 
not contain a trace of the preservative compound. 

" Sulphate of Copper, first suggested as a preservative by Mar- 
gary, and afterwards largely employed by Boucherie,may be used 
to prevent dry rot in timber, but for piers, bridges, and other 
structures which are exposed to the action of water, it has no 
practical value as the water dissolves out the salts with great 
rapidity. Timber prepared with this salt, and used for marine 
purposes, is as readily destroyed by the the Teredo and Limnoria as 
unprepared timber. 

"In Payne's process, a solution of Sulphate of Iron is first 
absorbed into the wood, and afterwards Carbonate of Soda. 
Double decomposition ensues, and the practical result is the form- 
ation of Oxide of Iron, the decomposition of which renders wood 
brittle, and does not prevent the attacks of either of the worms 
just named." 

Prof. Baird, of the Smithsonian Institute, in commenting upon 
a series of experiments conducted in Holland, under the direction 
of the Academy of Sciences of Amsterdam, says: 

* * Trial was made of Sulphate of Copper, 

Sulphate of Iron, Acetate of Lead, Corrosive Sublimate, Soluble 
Glass, Chloride of Calcium, and Chloride of Zinc, Tar Oil, 
Creosote of Oil, etc. Of these, the Creosote Oil experiment 
alone presented any positive indications of beneficial result, and 
in it the Committee found what they sought for. After five years 
of exposure, while all other piles, whether prepared or not, were 
entirety eaten up, those impregnated with this substance were 
perfectly sound and free from any trace of worms. * * * 
Impregnating wood with soluble inorganic salts which are 
poisonous to animal life, furnishes no protection against the 
worm. This is due to the fact that the sea water soon dissolves 
away their strength, and the worm does not devour or digest the 
wood bored out by means of the shelly jaws." 

Attempts have been made to obtain insoluble deposits in the 
interior of the timber by first injectiug a solution of o::e metalic 
salt, and afterwards forcing into the pores another soluiion which 
will combine chemically with the first and form a compound that 
water will not dissolve. This has failed in practice, for the reason 
that actual contact in the ligneous cells cannot be obtained. 
Surgeon-General Barnes of the U. S. Army, in his report on the 
preservation of wood pavements, says: "In those processes 
which design to fill the pores of the wood with insoluble substance 
(formed by a re-arrangement of several chemical compounds) the 
reaction which occurs is only partial, and confined to the super- 



6 

fices, being hindered by the formation of the insoluble salt, at 
and near the surface. * * * * My experiments 

show that it is always possible to dissolve and remove entirely 
any mineral or metalic salt which may have been deposited, with 
any degree of thoroughness, throughout a paving block." 

It is unnecessary to multiply authorities on this point. It may 
be considered as a settled fact that none of the metalic or mineral 
salts injected into timber will preserve it from the attacks of the 
marine worms. It is proper to add here, however, that some of 
the solutions referred to will prevent decay, and can be economi- 
cally applied. Sulphate of copper, applied as proposed by Thos. 
C. Wallace & Co., has been successfully used for the treatment of 
railroad ties and other timbers, both in the United States and 
Europe. The end of a green stick is enclosed in a close fitting 
collar, to which is attached an impervious bag communicating, 
through a flexible tube, with a reservoir containing the solution, 
elevated to a height of from thirty to forty feet. Hydrostatic 
pressure soon expels the sap and other fermentive matters at the 
opposite end of the stick. When the solution makes its appear- 
ance also, the process is completed. 

In 1846, eighty thousand sleepers of the most perishable wood, 
impregnated with sulphate of copper, were laid down on French 
railways. After nine years exposure, they were found as perfect 
as when laid. The experiment was so satisfactory that most of 
the railways in France at once adopted the system. 

It is claimed that this method of applying the material accom- 
plishes two objects — that of expelling the sap and of filling the 
pores with a preservative solution. The invention seems to be 
confined to the method of applying the solution; Messrs. Wallace 
& Co. offering, in their communication, to treat piles and timber 
with creosote oil, sulphate of copper, or any other well known 
solution. If creosote oil, or the dead oil of coal tar can be forced 
into piles by this apparatus, which I doubt, the process will give 
very satisfactory results. 

THE CREOSOTING PROCESSES. 

Creosote oil, or dead oil, as it is usually termed in the United 
States, is, so far, the only substance met with that furnishes a 
complete and perfect protection against the marine worm. It is 
obtained, by distillation from ordinary gas tar. In the East- 
ern States, forty barrels of tar will yield two barrels of benzine, 
ten barrels of dead oil, and about twenty-seven barrels of pitch. 
The benzine sells there at twenty-five cents, the dead oil at 
nine cents, and the pitch at thirteen cents per gallon. At nine 
cents per gallon, about one cent per pound, dead oil is the 
cheapest known material for the preservation of wood, and is also 
the best. The first successful application of creosote oil was made 
by Mr. John Bethel 1, who obtained a patent for his process in 



England in 1838. In his pamphlet, Mr. Bethell thus describes 
his process : 

" The timber, being first dried, and cut according to the pattern 
required, is carefully weighed, and is then placed in a cylinder of 
wrought iron, the doors of which are hermetically closed. The 
air and moisture contained in the wood are then exhausted from 
it, and from the cylinder containing it, by a powerful air pump. 
The pores of the wood being now empty, and capable of being 
absolutely filled, the preservative material, called creosote oil, 
(which consists of the heavy bituminous oils distilled from gas tar 
and pitch) heated up to 120° Fahr. is forced into the body of the 
timber by powerful hydrostatic pumps, exerting a pressure of 120 
to 200 lbs. per square inch. This pressure is maintained, until it 
appears that the proper quantity of creosote oil has entered the 
wood. The wood is then taken out and weighed, to verify the 
result." 

He states that the amount of oil required for railway sleepers, 
bridges, etc., is seven pounds to the cubic foot, and for marine 
purposes ten pounds to the cubic foot. 

Mr. Moir, in the paper before referred to, states: "Inno case, 
does the evidence regarding the value of the process seem to equal 
that in favor of the creosoting process, patented by Bethell. * 
Creosote acts very powerfully in coagulating the 
albumen contained in the cells of the wood, and besides this, it 
effectually preserves the fibre of the timber, and hence its value 
over all other so called preservative agents. 

" Since the creosoting process was first introduced in the year 
1838, it has been extensively employed in Great Britain and Ire- 
land; in all the countries on the continent where creosote oil can 
be obtained — France, Holland, Belgium, Germany, Spain, Port- 
ugal and Italy; and in India, Cape Colony, Brazil and other 
tropical countries, to preserve timber from the attacks of the 
white ant. Wherever it has been properly carried out, it has 
been completely successful. 

Mr. Brunei, Robt. Stevenson. Thomas McClean, A. Forrestier, 
M. Crepin, T. E. Harrison, Mr. Hawkshaw, and many other emi- 
nent engineers and scientific men concur in this estimate of the 
value of the creosote process. 

Dr. Letheby, the celebrated English chemist, states that creosote 
acts as a preservative agent in the following ways : 

1. It coagulates the albuminous substances and gives stability 
to the constituents of the cambium and cellulose of the young 
wood. 

2. It absorbs and appropriates the oxygen which is within the 
pores of the wood, and so checks, or rather prevents the erema- 
causis of the ligneous tissue. 



3. It resinifies within the pores of the wood, and in this way- 
shuts out both air and moisture. 

4. It acts as a positive poison to the lower forms of animal and 
vegetable life, and so protects the wood from the attacks of fungi, 
acari and other parasites. 

Under date of December 10th, 1870, Gen. Q. A. Gilmore, U. S. 
A., in a communication to Gen. A. A. Humphreys, Chief of 
EDgineers U.S.A., writes as follows : 

' ' After a careful inquiry concerning the various methods of 
preserving timber from decay, and from the attacks of land and 
marine worms, now practiced, I am convinced that the Bethell 
process, patented in England in 1838, and the two American mod- 
ifications of it, known respectively as the Seely, and Robins pro- 
cess, are both cheaper and more effectual than any other preserv- 
ative methods now in use. They consist in impregnating the 
timber to a greater or less degree with carbolic acid, contained in 
creosote of coal tar." 

Gen. T. J. Cram, of the U. S. Engineer Corps, while in charge 
of the improvement of the St. Clair Flats, in Michigan, submitted 
to Gen. Humphreys an interesting report on this subject, from 
which I copy the following tables : 

Results of Creosoting Wood for Railroad Ties, in Foreign Countries, 
compared with the duration of the same Wood uncreosoted,for Ties. 



NAME OF RAILWAY, AND AUTHORITY FOR 
THE EXPERIMENT. 



Manchester and Crewe R. R 

Building News, July 5, 1870. 

Cologne and Minden R. R 

G. Frerne, Inspector. 

India Railroads 

Mr. Burt, 

Stockton and Darlington R . R 

FThos. Summerson Inspector. 

Yorkshire and Lancashire R. R 

James Price. 

Middleb'o & Great Western R. R. . . . 

James Price. 

Great Eastern R. R 

Sam'l Dawson, Sup't. 

Belgium Railroads 

Minister of Public Works. 
Austrian, French, Prussian & Russian 

Railroads 

George Sheppard Page. 



T3 ^3 <d .^ ' 

l"o fart 

° o a os 

*S 2 Tj " -H 



American 
White Fir. 

Not stated. 

Not stated. 

Yellow 
Pine. 

Not stated. 

Red Baltic 
Fir. 

Scotch Fir, 

Red pine, 
oak, beech 

I Baltic Fir. 



co h 



, rt bi 



32 
12 
20 
26 
24 
9 
16 
19 



*}£. 



Perfectly 

sound . 
Perfectly 

sound. 
Perfectly 

sound. 
Perfectly 

sound. 
Perfectly 

sound. 
Perfectly 

sound. 
Perfectly 

sound. 
Perfectly 

sound. 



20 Perfectly 
sound. 



-a So .3 

0,0 3 O 
n e* «5 9 

rH i. X P 



Not stated. 

4 
Not stated. 

Not stated. 
Not stated. 
Not stated. 
Not stated. 



Results of Creosoting Wood in Foreign Countries, for props in Gol- 
leries, compared with the duration without treatment. 



PLACES OF EXPERIMENT AND AUTHORITY. 



South Durham Colliery 

Adam Hackworth, Overseer. 

Tanfield Moor Colliery 

James Joicy & Co. 

Mickley Colliery 

Mathew Liddell. 



Kind of 
wood creo- 
soted and 
used. 


CO CD 60 

S i I 

S.a§ 


Not stated. 


15 


Larch. 


7 


Larch. 


14 


Scotch Fir. 


14 



•5 G"vV 



Perfectly 
sound. 

Perfectly 
sound. 

Perfectly 
sound. 






%. of a year 

1% years 

only. 
6 years. 
4 years. 



Result o/* Creosoting for Marine Works. 



PLACES OF EXPERIMENT AND AUTHORITY. 



Ostend Harbor ... 

L. Crepin, Engineer, etc. 

Lieth Pier and Harbor 

Thomas Maclane, Engineer. 
Docks at Monk Wearmouth .... 
A. Forestier, Engineer. 

Tiegnmouth 

Mr. Brunei, Engineer. 

Grimsby 

Adam Smith, Engineer. 

Portland Breakwater 

John Code, Engineer. 



>d 


00 u 






O 


«*£ 


£,-,• 


>>^ bb 


















-3 £ 


o3m 


a g 




Baltic Fir. 


7 


Not stated. 


12 


Yellow 


20 


Pine. 


Not stated. 


7 


Not stated. 


7 


Not stated. 


4 



§•2 



H .cl 



No attack. 

sound. 
No attack. 

sound. 
No attack. 

sound. 
No attack. 

sound. 
No attack. 

sound. 
No attack. 

sound. 



'O 03 



6 £ >* 



- oo o 



2 

3% 
Not stated. 
Not stated. 

3 

3 



In reference to the foregoing tables, General Cram remarks : 
" It is to be observed, that at the expiration of the periods ex- 
pressed in the third columns of the tables, the timber which was 
treated, is reported perfectly sound; there is no evidence showing 
how much longer it will last; and I can find no evidence of any 
which has been creosoted having yet decayed, or having been 
attacked by worms." 

Upon General Cram's recommendation, the Government 
adopted the Seely process for the treatment of all the timber 
used in the improvement of the St. Clair Flats. 

This process consists in subjecting the wood to a temperature 
above the boiling point of water, and below 300° Fahr. while 
immersed in a bath of Creosote oil, for a sufficient length of time 
to expel the moisture. When the water is thus expelled, the 
pores contain only steam, and the hot oil is quickly replaced by 
a bath of cold oil, by means of which change the steam in the 
pores of the wood is condensed, and a vacuum formed into which 



10 

the oil is forced by atmospheric pressure and capilary attraction . 
Six to twelve pounds of Creosote oil to the cubic foot of wood is 
expended in this process; the amount depending on the use to 
which the wood is to be put. For piles or other timber exposed 
to the depredations of worms twelve pounds is used. 

In 1871, Mr. Calvin Brown, Civil Engineer, and Messrs. 
Hanscom and Varney, Naval Constructors at the Mare Island 
Navy Yard, were instructed by the Navy Department, to exam- 
ine the Robins process for preserving timber. Under date of 
July 21st, 1871, they made a report to the Department approving 
of the process, and recommending that it be applied to all timbers 
used at the Yard for the upper part of ship's frames, to keelsons, 
ceilings, clamps, beams, knees, etc.; also, to soft wood work for 
magazines, store rooms and cabins; to masts, spars, and all wood 
work for boats. They also recommended that it be applied to 
all materials required for piling, capping, planking, etc., for 
wharves and foundations, and, in a word, to nearly all timbers 
and lumber used for any purpose at the yard. 

Accompanying the report is a concise history of experiments 
made by them to determine the influence of the process on the 
strength of wood, and as to combustion hj fire. Also the result 
of their investigations to determine the influence of the process in 
preserving timber from decay and from the attacks of the Teredo 
Navalis. On this latter point they say: 

" "We visited the establishment of the Pacific Mail Steam Ship 
Company, in San Francisco, where we saw interesting evidence 
of the efficacy of the process in preserving piles from the destruc- 
tive operations of the marine worm. A pile of Oregon pine, 7J 
inches in diameter, had been prepared expressly for this experi- 
ment, by being first split through its center in its whole length in 
two portions. One of these portions was preserved in the usual 
manner of other timber, and the other left in the natural state. 
The two parts of the pile were then hooped together, the cleaved 
surfaces exactly fitting each other, and placed under water in a 
vertical position, being securely bolted to a stationary pile of the 
Company's wharf; the top of the prepared pile was always under 
high water at least three feet, aad about three-fourths of its 
entire length was constantly under water. The pile had remained 
in this position since July 1869, and consequently had been sub- 
jected to all the influence thereof, for twenty- two months. On 
being taken up in our presence, and a section sawed off the 
lower end, the unprepared portion was found to be penetrated by 
several large worms, while the prepared part remained entirely 
sound and intact." 

After citing other instances of like effect, they saj 7 : " While 
these experiments afford conclusive proof of the immunity of 
timber thus prepared from the Teredo Navalis, during the time 



11 



mentioned, there is no doubt in our minds, that a prolonged and 
indefinite exposure would be attended with the same perfect 
defence." 

The following tables show the result of their experiments to 
determine the influence of the process on the strength of wood. 
It will be obseived that the strength of the preserved wood in 
the case of California Laurel is 96 per cent, of that of unpre- 
served wood; in Eastern White Oak 88 per cent., and in Oregon 
Pine 90 per cent. " It was shown, however, on a comparison of 
the final series of trials with those first made, with wood freshly 
treated by the process, that the preserved specimens materially 
increased in its transverse strength, and in the trials with several 
specimens of Oregon Pine, which had been preserved two years, 
20 per cent, more resistance to breaking weight was observed. 
* * * * Our experiments in burning the preserved 
stood showed the thoroughness of the process, as illustrated in 
the specimens operated upon; the preserving materials had per- 
meated the whole mass of the sticks." 



Experiments in testing transverse strength of various woods at Navy 
Yard, Mare Island. Specimens of Wood 1 inch square sectional 
area, lengths between suppoj'ts, 2 feet. 



Name of Wood. 



Laurel . 


6 
10 


a 


6 


«< 


6 
10 


« 


6 


Eastern Oak 


9 
6 


a 


9 
6 


Oregon Pine 


1 

9 
5 

6 


(« 


1 


i<* 


4 


a 
(( 


1 

9 
6 
6 



No. of 
Pieces 



Preserved . . . 
do. .. 
do. .. 

Unpreserved 
do. 
do. 

Preserved . . 
do. . . 

Unpreserved 
do. . . . 

Preserve^ . . 
do. .. 
do. .. 
do. .. 

do. .. 

do. . 

Unpreserved 
do. 
do. 
do. 



Aver'ge break- 
age weight 
in pounds. 


273 lbs. " 
264 " 
375 " 


306 lbs. 
306 " 
388 " 


323 t>s. 
348 " 


290 lbs. 
395 " 


268 Rs. 
300 " 
354 " 
363 " 


443%" 


453 " 


384 " 
349 " 
390 " 
401 " 



297 Bos. 

329 lbs. 
333 Bbs. 
332 lbs. 

325 lbs. 
443%" 
453 " 

376 " 



A.v. deflection 
when broke 
(in inches) . 

1% 
IK 
IX 

1% 

1% 

2% 
1 11-12 



±/8 

2% 



1 

IK 

11-16 
11 1-16 



* These four pieces Oregon pine had been preserved nearly two years. 



12 

In regard to the influence of the process in preventing the de- 
cay of wood, Messrs. Brown, Hanscom and Varney say : "From 
the above facts, we are forced to admit the superiority of the 
prepared over the unprepared wood, in cases where exposure to 
earth soils exist, but to what length of time, beyond that herein 
observed, this superiority may be claimed, we have no means of 
possibly judging. We see no reason, however, for doubting that 
the sound condition of prepared wood may be continued many 
years." 

The Robins process, as practiced in San Francisco, is as 
follows : The bark being first removed from the piles, they are 
placed upon cars, some forty at a time, and hauled into a tank 
80 feet long, by 14 feet high, and 11 feet wide. The doors are 
then closed, and steam is let into the tank, at a low pressure, for 
the purpose of washing out from the wood the albumen, and any 
fermentative deposits left in it by the sap of the tree. After this 
steam washing, the wood is dried by means of a steam coil and 
ventilation, and is then ready to receive the oleaginous vapors. 
These vapors are generated from coal tar placed in a closed still, 
capable of holding 2,000 gallons. The first products of the tar, 
viz. : naptha and ammoniacal water, are allowed to pass off sepa- 
rately. When the thermometer in the top of the still indicates a 
heat of 220°, the vapors are turned upon the wood, and the still 
kept running until the same thermometer indicates a heat of 
420°. The firing under the still now ceases, but it remains con- 
nected with the tank for 10 or 12 hours longer, when the wood is 
preserved ready for use. It is hauled out the same way it went 
in, loading and discharging being done by steam. 

It is claimed by the patentees that while the piles thus treated, 
are not impregnated through and through when they come from 
the tank, yet the circumference has received a sufficient quanti- 
ty of the creosote to prevent the worms from effecting a lodge- 
ment on the surface of the pile. It is also claimed by the 
Robins ! patentees, that the process of impregnating the piles or 
square timber through and through, is completed by climatic 
influence, aided by the penetrating nature of the oils them- 
selves, after the wood is removed f^oin the tank. In small timber 
and planking, the process is completed before they are taken 
from the vapor bath. The patentees also claim and prove that 
the thorough impregnation of the wood in this vapor bath is only 
a question of time, and of consequent price per thousand feet. 

From what has now been shown, I think I am warranted in 
saying that the protection of timber against rot and marine 
worms, is narrowed down to the question as to the quantity of 
dead oil necessary to be injected into the pores of the wood. As 
stated repeatedly by the best authorities, a well creosoted piece 
of timber has never been known to rot or to be eaten by worms. 



13 

Our experience in this city in the use of preserved piles, com- 
pared with the experience of English engineers, gives us the two 
extremes in quantity of dead oil, injected into the wood. 

Bethell uses for piles, from 10 to 12 lbs per cubic foot. 

Seely, (at St. Clair Flats,) 4 Bbs . " 

Eobins, 1 lb " 

In each case the oils are those distilled from coal tar, heated 
above the boiling point of water, and the greater portion of them 
of a specific gravity slightly exceeding that of water. 

While we have no complete information as to the minimum 
quantity of oil that may be safely used to prevent the attacks of 
the marine worm, I believe it is generally conceded that it is 
unnecessary to pursue the treatment to the extent of saturating 
the timber, as in the Bethell process. The American Engineers 
— actuated by that spirit of economy which distinguishes them 
from their English brothers — have investigated this branch of the 
subject with characteristic energy and ingenuity. Mr. Herman 
Haupt, in an article published in Van Nostrand's Magazine, for 
May, 1872, says : " It is well known that the very small portion 
of creosote in smoke will penetrate to the interior of a ham, and 
cure it. The soluble portions of wood are only 4 per cent, of its 
weight. If, as high authorities assert, the five thousandth part 
of carbolic acid will prevent putrefaction of blood, fseces, glue 
solution, flour paste, and other substances liable to fermentation, 
the same proportion should protect the albuminous and soluble 
portions of wood. ' And if this be true, only the one hundred 
and twenty-five thousandth part of the weight of the wood would 
be required. This is less than the two hundred and fiftieth part 
of an ounce to a cubic foot, and more than this may be conveyed 
into paving blocks by the vapor process. While it seems probable 
that thorough saturation with oils, as in the Bethell process, is 
unnecessary, a much larger portion than the minimum required 
to prevent putrefaction would seem to be desirable." 

In the same article Mr. Haupt expresses an opinion adverse to 
the efficacy of the Bobins process, on the ground that the 
moisture in the pores of the wood is not expelled by the treat- 
ment, and that the vapors of the oil cannot, therefore, penetrate 
to the interior of the timber. On the other hand, we have the 
testimony of Mr. Calvin Brown that, in the specimens examined 
by him, " the preserving materials had permeated the whole mass 
of the stick." 

In 1871, desiring to test the thoroughness of the treatment, I 
obtained augur chips from a large n amber of piles which had been 
treated by the Bobins process, and submitted them to Professor 
Carr, of the State University, for examination. The chips were 



14 

separately taken, and duly labelled, at depths of one-half an inch 
from the circumference to the center of the pile, and at various 
intervals between the two ends. The following letter gives the 
result of Prof. Carr's examination : 

Univeesity of California, ) 
Oakland, Nov. 5th, 1871. ) 

T. J. Arnold, Esq. — Dear Sir : — I have carefully examined the 
specimens of wood you sent me, which have been subjected to 
the Eobins process, with the following result : 

1st. A large portion of the soluble nitrogenous (albuminous) 
matter has been removed, thus diminishing the natural tendency 
of the wood to decay, and facilitating the penetration of the 
vapors from coal tar. 

2d. The coal tar vapors have penetrated from one to three and 
a half inches from the surface, their presence being decidedly 
indicated in some instances at the latter depth. The well known 
preservative character of these vapors, and the repugnance of 
that scourge of our harbors, the teredo, to them indicate the value 
of the process, when faithfnlly conducted. 

Kespectfully Yours, 

EZEA S. CARR. 

In some experiments recently made by me, I observed the fol- 
lowing facts which I have no where seen noticed in published 
works on the subject. 

1. The oil penetrates the cellular tissue of the wood with great 
difficulty. 

2. The fibrous portion of the wood takes it up readily. 

3. Oil will penetrate sap wood across the grain, but heart wood 
receives it almost entirely in the direction of the grain. This 
fact is made very apparent by boiling wood in oil from two to 
three hours and then plunging it into a bath of cold oil. It will 
be found that the oil has penetrated entirely through the sap and 
there stopped; the heart seeming to form an impassable barrier 
to its further progress. 

When it is remembered that we use round timber, with the sap 
on, for piles, these facts may afford an explanation of the success 
of the Robins process as applied on this coast. 

In 1869, the Board of State Harbor Commissioners requested 
Col. Wm, J. Lewis, then the Engineer of the Board, to examine 
the subject of the preservation of wood and in June of that year 
Col. Lewis submitted an able report in favor of the Robins pro- 
cess as applied by the company managed by Mr. I. C. Woods. 



15 

The Harbor Commissioners thereupon entered into a contract 
with Mr. Woods to preserve the piles, caps, stringers and a por- 
tion of the planking used in the construction of the wharf along 
the bulkhead between Jackson and Pacific streets. More or less 
of preserved piles have been used in the construction of all 
wharves along the sea wall since 1869, though in later built 
wharves none of the caps and stringers have been preserved. I 
have recently examined the piles in the wharf between Jackson 
and Pacific streets by boring with an auger near the line of ex- 
treme low water. No worms were found in the preserved piles 
but some unpreserved piles in the same wharf, driven at the same 
time, nearly four years ago, were found to be worm eaten. The 
examination was not as thorough as could be wished, but it 
showed conclusively that the treatment has been a partial if not a 
complete protection against the attacks of the worm. I am not 
prepared to say that there are no worms in these piles, but the 
same tests applied to the preserved and unpreserved piles failed 
to develop them in the one case and did develop them in the other. 

Mr. Arthur Brown, Superintendent of Bridge Construction for 
the Central Pacific Bail Boad Co., informs me that he has lately 
taken up and thoroughly examined some piles which were treated 
by the Bobins process and driven at the company's wharf near 
the foot of Second street, two years ago. These piles were found 
to be perfectly sound, and free from worms, while other piles 
which had not been treated, driven at the same time and place, 
were found to be worm eaten. Worms, however, were found in 
a piece of sawed timber which had been treated by the vapor 
process. 

Some months ago, Capt. Cox of the Pacific Mail Steamship 
Company, also informed me, that he had made some experiments 
for the purpose of testing the value of the Bobins treatment. 
At that time the worms had not attacked the round timber, but 
he had found them in a piece of sawed timber which had been 
imperfectly preserved by the Bobins process. It is worthy of 
note that the company has ^ince used piles preserved by this 
process in an extensive addition which has lately been made to 
their wharf. I am also informed that the U. S. Engineers are 
using piles treated by this process at Mare Island, Lime Point, 
Fort Point and Wilmington, and that the Central Pacific B. B. 
Co. have recently had a large number of piles preserved in this 
manner. 

The element of time, so essential to the determination of the 
value of any wood preserving agent is wanting in the case of the 
Bobins process, but the results which have been obtained thus 
far, warrant the conclusion that it is economy and sound policy 
to treat by this process the piles and a portion, at least, of the 
superstructure of the wharves hereafter constructed. The price 



16 

now paid by the Board for piles driven, capped and bolted ap- 
proximates 50 cents per lineal foot; the extra cost of preserving is 
10 cents per lineal foot. We know from experience that fender 
piles unpreserved will not last over five years; we also know that 
preserved piles are not materially, if at all, injured after being 
driven nearly four years. Now assuming that four years is the 
limit of protection afforded by the treatment, it is still evident 
that it is economy to preserve the piles by the vapor process. 

In conclusion, I desire to say that while I am decidedly of the 
opinion that the vapor process, as practiced by -Mr. Woods, is the 
best that can now be procured on this coast, I believe it would be 
advisable to inject a larger quantity of dead oil into the timber ; 
and should any process or treatment be offered which would 
accomplish that object, I would recommend the Board to adopt 
it, even at a largely increased cost. 

Respectfully submitted, 

T. J. ARNOLD, 

Engineer Sea Wall. 






■■ ■^y-m 



LIBRARY OF CONGRESS - 

iiiiiffiiiwiHiniiiiiMiiiMigiiiEi 

020 364 838 8 



